Focusing device for light signals



March 3, 1931. TE 1,794,586

FOCUSING DEVICE FOR LIGHT SIGNALS Filed Aug, 25 1926 5 FIGS. 56.4.

nu u 1 Patented Mar. 3, 1931 \AINSLIE 'r. canrnn, or CO;LDWATER, ewYear, Assre'non To GENERAL RAILWAY j SIGNAL oomre'ntbr'noofins rnn, NEWYORK rooosrite nnvrcn ron LIGHT SIGNALS Application filed Au ust25,1926; Serial No. 131,467.

lhis'invention relates to light signals for railwaysignaling purposes,and more par ticularly to a device'ior making it easy to determine Whenalamp has been properly adjusted to have its filament on focus.

In the typical light signal, an incandescent lamp With a concentratedfilament is used in combinationiwith a lens, a mirror, or other suitablelight projecting means to project a light beam'of limited spread to giveaisignal indication, eitherjby virtue of ,its color or association withother-beams of light. 'In order to obtain the desired range and spread,it is essential that the'filament of the incan- 1 descent lamp belocated accurately at the focal point otthe light projecting unit. In-

candescent lamps, as ordinarily manufactured, have some variation inthelocation of the filament to a lamp base, so that when a nei vtlamp isput in alight-signahthe filament will. rarely come at-th'e exact focalpoint. To take care of. these variationsyit,

In accordanceavitlrthe present invention it isproposed to providesighting orfinding devices which will-. indicate when t heifilament ofthe lamp has-been adjusted to. the

to make such finders of, a simple construction so that they maybecheaply manufactured and" permanently, instal led1 as apart Y of eachsignal. Another object is to provide a finder which may be easily adjustededuring the process of assembling the signal, so.

that the finders will define/the right-point for the location of thelamp filament for that particular .signal,independently of accuracyofmachining the various parts; Alstillfurther obiject is to arrange thelines-of sight defined by the' findersiwith relation to the lines ofmovement of' the socket as'it is adjusted so as. to ,facilitatetheadjustment of the so c k otil f N right point.- jOne-obj'ect of theinventipn is Further objects and advantages of the invention Will beinpart apparent andin partpointed out as the "description pro s si theaccompanying drawings, shows a vertical sectionthrough a light signalembodying the invention, said section being transversely of the aXisofthe light projection unit and taken on the line l1 in Fig.2, r

, Fig 2 shows. another vertical section through the signalon-the axisofthe lens;

a Fig. 3 shows a longitudinal sectionthrough oneflof, the *finclersy 1:F. g. 4 is an endview of the finder; and

, Fig. 5 is 'a transverse section through the finder onth e line 55 inFig. 3. c -W'hile the invention may be applied to light signalsofvarious types it has been shown in the drawings in connection with asingle.light projecting unit. employing the Wellknoivn doublet lenscombination. This unit shown .is capable of emitting only one 'beam oflight of a: particular color, and in practice would be: combined Withthe other light units "giving other distinctivecolors; or severallikeunits Would be disposed in a predetermined relation, so as to give an indication by the disposition or arrangement of.

' the "lights of the same ordiiierent colors.

The various details.- and. characteristics of the light signal itselfare not material to the present invention;.and the particular form shownis merely representative.

; The signal nnit illustrated comprises a boxlike easing 1;,-hZLVl11g1tS back closed by a swinging-door 2 which is provided wit-lithe usualgaskets,-. ventilator, hinges and fasteners The-casing 1 is formed withopenings. 3 at the top and bottom. The bottom opening supporting bracketB, so. as to 'formaball andsocket connection, and the casing lis securedto this bracket:- by bolts 4. The

bracket (B in turn, is supported on a suitable pole 5, orthelike, ;beingadjustable thereon Fig. l y

PATENT: orricr;

3 receives ag rounded' projecting lug on the and held in place by screws6; The opening 3 atthe top, together, with thesimilar opening inthebottol nrof the."next casing superimposed on theone shown,prov1desconvenient pas:

sage for wires; but since only one casing is illustrated, this topopening is covered by a cover plate 7. To the front wall of the casing 1is secured the usual hood 8.

The inner and outer lenses 9 and 10 of the usual and well known doubletlens combination, are held by gaskets and bezel rings in the usual wayin a tapered lens barrel 11 which is secured in an opening in the frontwall of the casing 1 by bolts 12. The inner bezel ring 13, retaining theinner lens in place, is formed of an inverted U-shape, as

' shown in Fig. 1, and adjustably supports the lamp and the sightingdevice or finders o-f and back on lines substantially parallel with theaxis of the lens. Upturnedfianges'at the ends of the member 16 arefastened by bolts 18 to the lower ends of the inner bezel ring 18, saidbezel ring being formed with vertical slots 19 (see Fig. 1) throughwhich said bolts 18 pass, and the upturned flanges of the member16-being formedwith horizontal slots 20 for said bolts. Thus, the shelf16 may be moved up and down or sideways with relation to the axisof thelens. This way of supporting the socket 14 permits the lamp to be movedin and out, sideways in either direction, or up and down, with respectto the axis of the lens,.in anyone of three directions approximately atright angles. It should be understood that this adjustable support forthe socket'is merely illustrative, and that various other adjustablesupports permitting adjustment in these or similar directions may beemployed in connection with the finders or sighting devices about to bedescribed. p The incandescent lamp 15 is of any suitable construction,with a concentrated single or double filament located with respect toits basewith the usualmanufacturing inaccuracies. 7

The finders, designated as aswh'ole F, are fastened to the inner bezelring'l3 to provide lines of sight substantially at right anglesto eachother and parallel with the directions in which the socket may beadjusted up or down and sidewise. Referring particularly to- Figs. 3, 4and 5, each finder comprisesa base 22, with holes for the screws 23fasten ing the finder to the bezel ring. To this base 22 is fastened atubular'extension 24, having ii shaped notch designated 25 cut in oneside. This tubularextension24 may be secured to the base 22 in anysuitable manner by soldering, sweating in, or spinning. The

outer end of the tubular extension 24 is formed with a longitudinal slot26 (see Fig. 5), for the purpose hereinafter explained. The tubularextension 24 supports the tube 27 constituting the sighting device orfinder proper.

The outer end of this sighting tube 27 is covered by a piece of groundglass 28 held in place by a ring 29, soldered or otherwise suitablysecured'to the end of the tube. On this ground glass is placed suitablepoint designating marks, such as the cross hairs 30 (see Fig. 4),although spots, small rings, or the like may be employed. At anintermediate point in the length of the sighting tube is a partition 31with a central small pin hole 32. To fasten this partition 31 in place,the tube 27 is prefer-ably slotted transversely about half-way down, andthe partition inserted and sweated or soldered in place. This partition31 is preferably made as thin as practicable, and the hole 32'relativelysmall so as to'form an efiicient light directing means. The inner end ofthe tube 27 is formed with a V-sliaped slot; and a plate 33, inclined atabout degrees to the axis of the tube, is secured by solder or the liketo the tube at one edge of this opening, as shown in Fig. 3. mirror 34.'As shown, small retaining ears are pressed out of the plate 33 and bentdown over the edge of the mirror 34 to hold it in place. I

, Since small inaccuracies in the location and size of holes, alignmentof finished surfaces,

and the like, are unavoidable in practical manufacture, it is notexpedient to attempt to make the finders F and assemble them on thebezel ring 13 with the expectation that they will accurately define aparticular point with'reference to the bezel ring. Also, smallvariations inthe lenses themselves, and in their supporting elements,prevent the correct focal point for a given lens combination alwaysbeing at a fixed space relation to the inner bezel ring 13.Consequently, in practicing this invention, it is proposed to assemble"the parts asth-ey happen to come,

put alight in the socket and light it, and then 1;;

adjustthe'socket, irrespective of the -finders F, until the filament ofthe lamp-is at the correct point to givea beam of the desired intensityand spread. This condition is obtained by direct observation of the beamof light itself; and while this may be done by viewing the signal from adistance, the adjustment .of the lamp socket to put the filament onfocus is preferably made in a darkened room, inwhich there is a screenwith marks thereon to define the proper size of the beam for theselected distance between thesignal and the screen. 7

Having determined in this way the proper point for the filament of thatparticular sig- To this plate 33 is secured a small nal, the problem isto have the finders Fdefine that particular point, so that-the filamentsof other lamps may be adjusted to that same point and be focused for themost eilicient beam for that particular signal. Hth the filamentlighted, its image is reflected by the mirror 34 of each finder Fthrough the pin hole 82, which has the effect of a lens, and ontoan'image receptive'surface in the Y form of ground glass 28. The imageof the filament is sharply defined on the ground glass 28, and is largeror smaller than the actual image, depending upon the comparativedistances between the pinhole 32, which acts as a light directing devicesomewhat similar to a lens, and the mirror 34, and ground glass 28. Inshort, for a given markon the ground glass, or ch find-eraccuratelydefines a sighting line. i

lVhile the finders may be made to define the point at which a properlyfocused filament is located by putting the cross hairs on the ground tomark the point Where the image actually comes after the assembly and thefocusing operation just explained, the various inaccuracies might bringsuch marks on the ground glass off to one side, limiting the field ofthe finder; and rather than correct the inaccuracy in the constructionand location of the finders by marking the cross hairs in the rightplace it is preferred to make the finder proper, including the mirror,pin hole, and ground glass, adjustable on its support. In the particularconstruction shown, the tube 27, when first assembled, may be moved inor out, or turned; and by these movements it is possible to bring theimage on the cross hairs 30. The tube 27 is then permanently secured toits supporting base 22 bylrunning solder into the slot 26 in the tubularextension 24:. In this way, the finders may be readily adjusted in spiteof inaccuracies in the menu facture and assembly of the parts, and afteradjustment may be permanentlyfixed in position for the particularsignal. This proc-edure of determining-the focal point of a signal byactual inspection, and adjusting and fastening thefinders in position todefine the correct focal point can be easily perground glass 28 of-eachfinder, the socket is then adjusted in or out, up or down, or' sidewise,as the case maybe,'to bring thefilament of that particular new lamp attheright point prescribed by the finders.

The finders F afford two lines of sight intersecting at right angles ina common plane; and these lines of sight are made parallel with thedirections in which. the socket and the lamp filament more-as thesocketisadjustcd upa'nddown orsideW-ise in said plane.

After the e zlrety-has-been moved in or out alo -1 the axis of the-lensto brin the lam 3 i filament in the, common-plane of the lines ofsightof the finders, then the adjustments up erence tothe exactfocalflpoint so asto obtain the greatest efficiency; from the filament;

The images of the filament stand out clearly onthe groundiglassesof thefinders, evenin daylight, and in position where theycan be easilyobserved while adjusting the lamp,

so that the procedure of adjusting a1 lampis carried out-to muchbetteradvantage; than if theoperator had to peep through asightingopening; Various other practicaljad-v vantages of the filament sighting.arrangement. of this invention wlll lee: apparent Ito those-skilledintheart. 5 a

' lVhile the invention has been described with reference to one specificconstruction and arrangement of parts,l;desire-to'haveit understood thatthis construction is susceptible, of various adaptationsandamodifications without departing fi'olntlie functions and principlescharacterizing the invention.

hat I claim is v1. Fomsin means for lamps for light signals comprising,in combination with a lens and a support'bemfing a fixed relationthereto, a lampsocket adjustably attached to said support forindependent movement in three directions substantially at right anglesto each other, one direction being along the axis of said lens, two likeoptical finders each comprising a telescopically related base andsighting tube, each sighting tube having a mirror directly exposed tolight from alamp in said socket and an image receptive sur face withpoint identifying marks thereon,

and means permanently securing the bases of said finders to said supportwith the axes of their sighting tubes parallel with the axis of the lensand separated substantially 9O degrees in a planetransverse to saidaxis,

- 2. In alight signal, the combination with a lens and an adjustablelamp support, of an optical device for indicating when a lightedfilamentof alamp in said socket lies in a sighting l1ne,-sa1d optlcaldevice comprising a tube disposed with itsaxis substantially parallel tothe axisof the lens, a mirror at one end of the tube inclinedsubstantially l5.

degrees to itsaxis, and directly exposedto light from a lamp in saidsocket, means at the other end of said tube constituting an imagereceptive surface" having point identifying' marks thereon, IIIBEIIISVHIthe tube for projecting an image of a lighted filament refiected fromthe mirror onto said receptive surface, a base supporting said tube, andmeans fixing the base with respect to said optica'lfdevice. 1 o s 3. Ina light signal, a lens, a retaining ring bearing against the inside edgeof said lens, a lamp and socket therefor disposed With their axestransverse to the axis of the lens and adjustably supported by saidringto move in three directions substantially at right angles to each other,one of said directions being substantially parallel to the axis of thelens, two finders of the same construction fixed to saidring'substantially 90 degrees apart and defining sighting lines parallelwith said two directions-in which said lamp socket may be movedtransversely to the axis of said lens, each finder comprising a basefastened to thering and a tube received in said base for movement alongand about the axis ofsaid tube, a mirror nearthe end of each tubeinclined substantially 45 degrees to I i v its axis, a ground glass withpoint identifying' marks thereon at the other end of said tube, means insaid tube for projecting the image of a lighted filament reflected fromsaid mirror onto said ground glass, said tubes extending" substantiallyparallel with the axis of the lens and having their ground glasses bothvisible at'the same time from the rear of the signal.

Intestimony whereof I hereby aifix my signature. 5 v

AINSLIE T. CARTER.

